This is the firmware for the TNC3 version 2.1.1 hardware.

Building

Use Eclipse with CDT and the GNU MCU Eclipse plugins.

If you are porting this to another build platform, you will need to build the firmware using the same compiler and linker options. As with most firmware projects, there is a linker script with defines the memory layout for for the Flash and SRAM.

Blaze Dependency

There is a new dependency as of 2.4.3 with the addition of the Kalman filter. The firmware has a dependency on the Blaze C++ math library.

mkdir blaze
ln -s /usr/include/blaze blaze/

This also requires (for now) that the firmware be built with exceptions enabled.

Example GCC Command-line

Below are example compilation and linking lines for reference:

arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=softfp -mfpu=fpv4-sp-d16 -O2 -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -fno-inline-functions -fsingle-precision-constant -fstack-usage -fstrict-aliasing -ffast-math -Wall -Wextra -Wlogical-op -Wfloat-equal -g3 -D__FPU_PRESENT=1 -DUSE_HAL_DRIVER -DARM_MATH_CM4 -D__weak=__attribute__((weak)) -DSTM32L433xx -I/usr/arm-none-eabi/include -I../Inc -I../Drivers/STM32L4xx_HAL_Driver/Inc -I../Drivers/CMSIS/Include -I../Drivers/CMSIS/Device/ST/STM32L4xx/Include -I../Middlewares/Third_Party/FreeRTOS/Source/include -I../Middlewares/Third_Party/FreeRTOS/Source/CMSIS_RTOS -I../Middlewares/Third_Party/FreeRTOS/Source/portable/GCC/ARM_CM4F -I../TNC -I../Middlewares/ST/STM32_USB_Device_Library/Class/CDC/Inc/ -I../Middlewares/ST/STM32_USB_Device_Library/Core/Inc -std=gnu11 -Wmissing-prototypes -Wstrict-prototypes -Wbad-function-cast -c -o Src/stm32l4xx_it.o ../Src/stm32l4xx_it.c 
arm-none-eabi-g++ -mcpu=cortex-m4 -mthumb -mfloat-abi=softfp -mfpu=fpv4-sp-d16 -O2 -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -fno-inline-functions -fsingle-precision-constant -fstack-usage -fstrict-aliasing -ffast-math -Wall -Wextra -Wlogical-op -Wfloat-equal -g3 -T /home/rob/TNC3/firmware/STM32L433CCUx_FLASH.ld -Xlinker --gc-sections -Wl,-Map,firmware.map --specs=nano.specs -o firmware.elf Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_adc.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_adc_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_cortex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_crc.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_crc_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_dac.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_dac_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_dma.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_dma_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_flash.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_flash_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_flash_ramfunc.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_gpio.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_i2c.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_i2c_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_iwdg.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_opamp.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_opamp_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_pcd.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_pcd_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_pwr.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_pwr_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_rcc.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_rcc_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_rng.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_rtc.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_rtc_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_tim.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_tim_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_uart.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_uart_ex.o Drivers/STM32L4xx_HAL_Driver/Src/stm32l4xx_ll_usb.o Middlewares/ST/STM32_USB_Device_Library/Class/CDC/Src/usbd_cdc.o Middlewares/ST/STM32_USB_Device_Library/Core/Src/usbd_core.o Middlewares/ST/STM32_USB_Device_Library/Core/Src/usbd_ctlreq.o Middlewares/ST/STM32_USB_Device_Library/Core/Src/usbd_ioreq.o Middlewares/Third_Party/FreeRTOS/Source/CMSIS_RTOS/cmsis_os.o Middlewares/Third_Party/FreeRTOS/Source/croutine.o Middlewares/Third_Party/FreeRTOS/Source/event_groups.o Middlewares/Third_Party/FreeRTOS/Source/list.o Middlewares/Third_Party/FreeRTOS/Source/portable/GCC/ARM_CM4F/port.o Middlewares/Third_Party/FreeRTOS/Source/portable/MemMang/heap_3.o Middlewares/Third_Party/FreeRTOS/Source/queue.o Middlewares/Third_Party/FreeRTOS/Source/stream_buffer.o Middlewares/Third_Party/FreeRTOS/Source/tasks.o Middlewares/Third_Party/FreeRTOS/Source/timers.o Src/arm_fir_f32.o Src/arm_fir_fast_q15.o Src/arm_fir_init_f32.o Src/arm_fir_init_q15.o Src/arm_fir_interpolate_init_q15.o Src/arm_fir_interpolate_q15.o Src/arm_offset_q15.o Src/arm_q15_to_float.o Src/freertos.o Src/main.o Src/stm32l4xx_hal_msp.o Src/stm32l4xx_hal_timebase_TIM.o Src/stm32l4xx_it.o Src/system_stm32l4xx.o Src/usb_device.o Src/usbd_cdc_if.o Src/usbd_conf.o Src/usbd_desc.o TNC/AFSKModulator.o TNC/AFSKTestTone.o TNC/Afsk1200Demodulator.o TNC/AfskDemodulator.o TNC/AudioInput.o TNC/AudioLevel.o TNC/DCD.o TNC/Demodulator.o TNC/Digipeater.o TNC/FilterCoefficients.o TNC/Fsk9600Demodulator.o TNC/Fsk9600Modulator.o TNC/Goertzel.o TNC/Golay24.o TNC/HdlcDecoder.o TNC/HdlcFrame.o TNC/IOEventTask.o TNC/Kiss.o TNC/KissHardware.o TNC/KissTask.o TNC/LEDIndicator.o TNC/Log.o TNC/M17.o TNC/M17Demodulator.o TNC/M17Encoder.o TNC/M17Modulator.o TNC/ModulatorTask.o TNC/NullPort.o TNC/PortInterface.o TNC/PowerMode.o TNC/SerialPort.o TNC/UsbPort.o TNC/bm78.o TNC/bm78_eeprom.o newlib/_exit.o newlib/_sbrk.o newlib/_syscalls.o startup/startup_stm32l433xx.o 

Debugging

Logging is enabled in debug builds and is output via ITM (SWO). The firmware is distributed with an openocd stlink config file that enables ITM output to a named pipe -- swv. You must create this pipe in the top level directory.

To read from this pipe, open a terminal and run:

while true; do tr -d '\01' < swv; done

If you change the MCU's core clock, you need to adjust the timing in the stlink-tnc3.cfg config file.

The TNC3 runs at 48MHz on startup. It may switch to 80MHz for modulation types such as 9600 or M17 which require more speed. This makes using SWO challenging as it cannot handle changes in core speeds.

Installing firmware

Firmware can be installed via the on-board ST/LINK port or via USB DFU.

USB DFU

1. Download the STM32CubeProgrammer. https://s3.amazonaws.com/mobilinkd/en.stm32cubeprog-1.4.0.zip This programmer will work on Linux, OS X, and Windows.

2. Download the ELF file from the release (or that you have built from source).

3. Plug the TNC into a USB port and turn the TNC on. You should see a USB serial port enumerated.

4. Put the TNC into DFU mode by pressing the DFU/boot button on the side. The TNC will only enter DFU mode when plugged into a USB port.

There is no visible indication on the TNC that it is in DFU mode

5. You should see the serial port device go away and a new DFU device appear.

6. Run the STM32CubeProgrammer from the command-line. (Replace "firmware.elf" with the appropriate firmware filename. It must be in ELF format.)

   ./STM32_Programmer_CLI -c port=USB1 -d firmware.elf -v -g 0x8000000

7. When that is complete, the DFU device will disappear and the serial port device will re-appear.

Development Notes

IWDG

The independent watchdog is used to prevent the TNC from locking up in an undefined state. The watchdog ensures that:

1. The event loop is called on a regular interval.
2. The packet buffer pool is not exhausted.
3. The modulator is not stuck on.

The watchdog is updated in the event loop at least once every 100ms as long as the buffer pool is not exhausted and PTT is not held.

When PTT is held, the modulator holding PTT is responsible for updating the watchdog.

FreeRTOS Settings

Tickless Idle

It is vital that Tickless Idle is not enabled. This feature seems to have serious problems with changes to the sysclock. And the TNC3 firmware changes the sysclock between 16MHz (startup), 2MHz (Disconnected, on battery), 48MHz (USB, or BT connected), and 72MHz (if needed by modem).

The symptoms that occurs when tickless idle is enabled is that certain interrupts are no longer serviced. This prevents the USB subsystem from working, the RGB LED from being updated, and, at times, the event loop from being serviced.